Please describe three (3) methods for calculating the value of an annuity of $100 per year for 5 years starting at t1 using a 6% discount rate. What is the PV of this annuity?

Draw a clearly marked number line demonstrating how this annuity is the difference between

two perpetuities and show your calculations. Generally speaking, what is the purpose of discounting future cash flows?

I just need to see the number line please.